This article reports on the results of a corpus-based investigation of the functions of the “cognition verb + que-clause” complementation structure in Spanish. We will show that the interpretation of this pattern depends on the choice between subject and speaker perspective, and on the use made of both perspectives in descriptive and argumentative contexts. These two axes, perspective and use, determine the involvement of the speaker in the propositional content of the complement clause. Various configurations of speaker involvement can thus be identified.